KCDW, it might not really make up your mind but...
Screen readability and bluetooth connections are a non-issue in my experience. If it's bright you turn the backlight off and it works just fine (not fantastic, but definitely workable) and if it's dull you put the back light on. I've never had a single bluetooth connection problem after many hours of use.
Mounts are slightly trickier, but a good quality suction cup will do if you aren't up for making something out of bits and bobs.
At the end of the day, despite having a bucket load of this kind of kit laying around I tend to use a dedicated Garmin GPS (the 196 in my case). I find it more reliable (never crashes), the battery life is better, the plug-in power lead works with a 28V system, the buttons work better in rough air, etc.
MemoryMap with CAA charts is nice, but not very good for IFR flight. AnywhereMap would be great if it had a decent database (it's good in the US where they do have). None of the other pieces of software I've tried have proven to be reliable or stable for me on various ipaqs.
So my choice is a dedicated Garmin. If you want road navigation then buy TomTom (software only, about a hundred quid) and a lead to link your ipaq to the Garmin (about 20 quid). It's a bit of a fag having to have both units in the car, but it'll work if you don't want to have to buy a GPS just for in-car navigation.